Working Around Nuke Design Flaw

Tuesday, January 11, 2011 @ 11:01 AM gHale

Engineering workers at the nuclear power plant near Berwick, PA, detected a design flaw in a temperature control system that could have shut down the two reactors, the Nuclear Regulatory Commission (NRC) reported.

Despite the finding, the reactors remain in operation, and officials at the PPL’s Susquehanna Steam Electric Station are working to correct the problem that has existed since the plant came on line in the 1980s, said Neil Sheehan, an NRC spokesman.

PPL Susquehanna LLC and Allegheny Electric Cooperative Inc. jointly own the plant.

Inhouse experts discovered the flaw and then reported it to the NRC, Sheehan said.

Sheehan described the flaw as a “single point of vulnerability.” Besides resulting in a shut down, he said, “this could have impacted some very important safety systems.”

Plant spokesman Joe Scopelliti said plant operators have taken measures to make sure it operates safely.

Relying on the temperature control system is a key element at the plant. With equipment and system upgrades completed during a refueling and maintenance outage last spring, Unit 1 at PPL’s Susquehanna nuclear power plant is now the largest Boiling Water Reactor in terms of thermal power and generating capacity in the United States, according to the NRC.

When operating at 100 percent power, Susquehanna’s Unit 1 has a capacity of 3,952 megawatts thermal (a measure of the heat produced in the reactor) and about 1,300 megawatts electrical (a measure of the electricity produced by the generator). The 1,300 megawatts of electrical output is enough to power about 1 million typical homes.

Workers completed equipment upgrades during the outage that enables Unit 1 to produce more steam and generate more electricity. One of the upgrades included the installation of a new integrated digital control system for plant equipment and replacing turbines that power pumps that provide water to the reactor vessel.

The completion of upgrades during this year’s Unit 1 outage continues a four-year project started in 2008 to increase the amount of electricity the Susquehanna nuclear plant can generate. That project should conclude this year after completing further upgrades to Unit 2. When completed, Unit 2 will have a similar capacity for thermal and electrical energy.